Etchant composition, method of etching insulating film, method of manufacturing semiconductor device, and silane compound

ABSTRACT

An etchant composition includes a silane compound represented by the following Chemical Formula 1: 
     
       
         
         
             
             
         
       
         
         
           
             wherein R 1  to R 6  are independently hydrogen, halogen, a substituted or unsubstituted C 1 -C 20  hydrocarbyl group, a phenyl group, a C 1 -C 20  alkoxy group, a carboxy group, a carbonyl group, a nitro group, a tri (C 1 -C 20 )alkylsilyl group, a phosphoryl group, or a cyano group, L is a direct bond or C 1 -C 3  hydrocarbylene, A is an n-valent radical, and n is an integer of 1 to 4.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims benefit of priority to Korean Patent ApplicationNo. 10-2018-0060001 filed on May 26, 2018 and 10-2018-0127497 filed onOct. 24, 2018 in the Korean Intellectual Property Office, the disclosureof which is incorporated herein by reference in its entirety.

BACKGROUND 1. Field

The present disclosure relates to an etchant composition, and moreparticularly, to an etchant composition having a high selection ratiowhich may selectively remove a nitride film while minimizing an etchingrate of an oxide film, a method of etching an insulating film, and amethod of manufacturing a semiconductor device. In addition, the presentdisclosure relates a silane compound which is appropriate for use as anadditive of the etchant composition.

2. Description of Related Art

An oxide film such as a silicon oxide (SiO₂) film and a nitride filmsuch as a silicon nitride (SiNx) film are representative insulatorfilms, and in a semiconductor manufacturing process, the silicon oxidefilm or the silicon nitride film is used alone or in the form of alaminate in which one or more films are alternately stacked. Inaddition, the oxide film or the nitride film is also used as a hard maskfor forming a conductive pattern such as a metal wiring.

In a wet etching process for removing the nitride film, a mixture ofphosphoric acid and deionized water is generally used. The deionizedwater is added for preventing a decrease in an etching rate and a changein etching selectivity to an oxide film; however, there is a problem inthat defects arise in a nitride film etching removal process even with aminute change in an amount of supplied deionized water. In addition,phosphoric acid is a strong acid and corrosive, thereby having adifficulty in handling.

In order to solve the problem, there is a conventionally knowntechnology for removing a nitride film using an etchant compositionincluding fluoric acid (HF), nitric acid (HNO₃), or the like inphosphoric acid (H₃PO₄), but causing a result of inhibiting an etchingselection ratio of the nitride film and the oxide film. In addition,there is also known a technology of using an etchant compositionincluding phosphoric acid and a silicate or silicic acid; however, thesilicic acid or silicate has a problem of causing particles which mayaffect a substrate, thereby being somewhat inappropriate for asemiconductor manufacturing process.

Meanwhile, when phosphoric acid is used in a wet etching process forremoving the nitride film, not only the nitride film but also an SODoxide film is etched due to a reduced etching selection ratio betweenthe nitride film and the oxide film, whereby it is difficult to adjustan effective field oxide height (EFH). Accordingly, a sufficient wetetching time for removing the nitride film may not be secured, or anadditional process is needed, which causes a change and has a badinfluence on device characteristics.

Therefore, an etchant composition having a high selection ratio, whichselectively etches a nitride film to an oxide film and does not have aproblem such as particle occurrence in a semiconductor manufacturingprocess, is currently demanded.

SUMMARY

An aspect of the present disclosure may provide an etchant compositionhaving a high selection ratio, which may selectively remove a nitridefilm while minimizing an etching rate of an oxide film, and does nothave problems such as particle occurrence having a bad influence ondevice characteristics, and a silane compound used in the etchantcomposition.

According to an aspect of the present disclosure, an etchant compositionmay include phosphoric acid and a silane compound represented by thefollowing Chemical Formula 1:

wherein R¹ to R⁶ are independently hydrogen, halogen, a substituted orunsubstituted C_(l)-C₂₀ hydrocarbyl group, a C₁-C₂₀ alkoxy group, acarboxy group, a carbonyl group, a nitro group, a tri(C₁-C₂₀)alkylsilylgroup, a phosphoryl group, or a cyano group, L is a direct bond or C₁-C₃hydrocarbylene, A is an n-valent radical, and n is an integer of 1 to 4.

According to an exemplary embodiment, the substituted or unsubstitutedC₁-C₂₀ hydrocarbyl group is a substituted or unsubstituted C₁-C₂₀ alkylgroup or a substituted or unsubstituted C₆-C₂₀ aryl group, and thesubstituted C₁-C₂₀ hydrocarbyl group may be substituted by halogen.

According to an exemplary embodiment, the etchant composition wherein Ais C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl, a radical having N as abinding site, a radical having S as a binding site, or a radical havingP as a binding site, is provided.

According to an exemplary embodiment, the etchant composition whereinthe radical having N as a binding site is *—NR¹¹R¹², *—NR¹³—*,*—NR¹⁴CONR¹⁵—*, *—NR¹⁶CSNR¹⁷—*, or

is provided, wherein R¹¹ and R¹² are independently hydrogen, C₁-C₂₀alkyl, C₁-C₂₀ aminoalkyl, or CONH₂, R¹³ to R¹⁷ are independentlyhydrogen or C₁-C₂₀ alkyl, and L₁ is C₁-C₂₀ alkylene.

According to an exemplary embodiment, the etchant composition whereinthe radical having S as a binding site is

*—S—*, *—S—S—*, is provided.

According to an exemplary embodiment, the etchant composition whereinthe radical having P as a binding site is

is provided, wherein R¹⁸ and R¹⁹ are independently hydrogen, C₁-C₂₀alkyl, C₆-C₂₀ aryl, or (C₁-C₂₀)alkyl(C₁-C₂₀)alkoxy.

According to an exemplary embodiment, the etchant composition wherein inChemical Formula 1, n is 1, L is a direct bond or C₁-C₃ alkylene, A is asubstituted or unsubstituted C₁-C₂₀ alkyl, a substituted orunsubstituted C₁-C₂₀ alkenyl, *—NH₂,*—NH—(CH₂)₁—NH₂, *—NH—CO—NH₂, or*—(CH₂)_(m)—C₆H₅, and 1 and m is independently an integer of 0 to 10, isprovided.

According to an exemplary embodiment, the etchant composition wherein inChemical Formula 1, n is 2, L is a direct bond or C₁-C₃ alkylene, A isC₁-C₂₀ alkylene, *—NR¹³—*, *—NR¹⁴—CO—NR¹⁵—*, *—S—*, *—S—S—*,

R¹³ to R¹⁵, R¹⁸, and R¹⁹ are independently hydrogen, C₁-C₂₀ alkyl,C₆-C₂₀ aryl, or (C₁-C₂₀)alkyl(C₁-C₂₀)alkoxy, is provided.

According to an exemplary embodiment, the etchant composition wherein inChemical Formula 1, n is 3, L is a direct bond or C₁-C₃ alkylene, and Ais

is provided.

According to an exemplary embodiment, the etchant composition wherein inChemical Formula 1, n is 4, L is C₁-C₃ alkylene, A is

wherein L₁ is C₁-C₁₀ alkylene, is provided.

According to an exemplary embodiment, the etchant composition whereinthe silane compound is selected from compounds represented by StructuralFormulae (1) to (28), is provided:

According to an exemplary embodiment, the etchant composition whereinthe silane compound is included in an amount of 0.001 to 1 wt %, basedon the total weight of the etchant composition, is provided.

According to an exemplary embodiment, the etchant composition furtherincluding a silane compound represented by the following ChemicalFormula 2, is provided.

According to an exemplary embodiment, it is preferable that in ChemicalFormula 1, R¹ to R⁶ are hydrogen, and also R¹ is a substituted orunsubstituted hydrocarbyl, and R² to R⁶ are hydrogen.

wherein R⁵¹ to R⁵⁴ are independently of each other hydrogen,hydrocarbyl, or heterohydrocarbyl, in which R⁵¹ to R⁵⁴ existrespectively or two or more of R⁵¹ to R⁵⁴ form a ring connected to eachother by a heteroelement.

According to an exemplary embodiment, the etchant composition furtherincluding an ammonium salt is provided.

According to another aspect of the present disclosure, a method ofetching an insulating film using the etchant composition is provided.

According to another aspect of the present disclosure, a method ofmanufacturing a semiconductor device may include the method of etchingan insulating film.

According to another aspect of the present disclosure, a silane compoundrepresented by the following Chemical Formula 1, which is appropriatefor addition to the etchant composition, is provided.

According to another aspect of the present disclosure, a silane compoundrepresented by the following Chemical Formula 1 is provided:

wherein R¹ to R⁶ are independently hydrogen, halogen, a substituted orunsubstituted C₁-C₂₀ hydrocarbyl group, a C₁-C₂₀ alkoxy group, a carboxygroup, a carbonyl group, a nitro group, a tri (C₁-C₂₀)alkylsilyl group,a phosphoryl group, or a cyano group, L is a direct bond or C₁-C₃alkylene, n is 4, A is

as a tetravalent radical, and L₁ is C₁-C₁₀ alkylene.

According to an exemplary embodiment, the silane compound whereinChemical Formula 1 is represented by the following structure, isprovided:

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIGS. 1 and 2 are process sectional views showing a device separationprocess of a flash memory device.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments in the present disclosure will now bedescribed in detail with reference to the accompanying drawings.

Since the present disclosure may be variously modified and have severalexemplary embodiments, specific exemplary embodiments will be shown inthe embodiment and be described in detail in the detailed description.However, it is to be understood that the present disclosure is notlimited to a specific exemplary embodiment, but includes allmodifications, equivalents, and substitutions without departing from thescope and spirit of the present disclosure.

Terms used in the present disclosure are used only in order to describespecific exemplary embodiments rather than limiting the presentdisclosure. Singular forms are intended to include plural forms unlessotherwise indicated contextually. It will be further understood that theterms “comprises” or “have” used in this specification, specify thepresence of stated features, steps, operations, components, parts, or acombination thereof, but do not preclude the presence or addition of oneor more other features, numerals, steps, operations, components, parts,or a combination thereof.

An etchant composition according to an exemplary embodiment of thepresent disclosure includes phosphoric acid and a silane compound.

The phosphoric acid may be reacted with silicon nitride to etch thenitride. The silicon nitride and the phosphoric acid may be reacted andetched as shown in the following Formula (1):3Si₃N₄+27H₂O+4H₃PO₄→4(NH₄)₃PO₄+9SiO₂H₂O  (1)

The phosphoric acid may be, for example, an aqueous phosphoric acidsolution containing phosphoric acid at a concentration of 80%, but notlimited thereto. Water to be used in the aqueous phosphoric acidsolution is not particularly limited, but is preferably deionized water.

The silane compound may be represented by the following Chemical Formula1:

In Chemical Formula 1, R¹ to R⁶ may be independently hydrogen, halogen,a substituted or unsubstituted C₁-C₂₀ hydrocarbyl group, a C₁-C₂₀ alkoxygroup, a carboxy group, a carbonyl group, a nitro group, a tri(C₁-C₂₀)alkylsilyl group, a phosphoryl group, or a cyano group. Morepreferably, in Chemical Formula 1, R¹ to R⁶ may be hydrogen, and also R¹may be a substituted or unsubstituted C₁-C₂₀ hydrocarbyl, and R² to R⁶may be hydrogen.

The substituted or unsubstituted C₁-C₂₀ hydrocarbyl group may be asubstituted or unsubstituted C₁-C₂₀ alkyl group or a substituted orunsubstituted C₆-C₂₀ aryl group, wherein the substituted hydrocarbylgroup may be a hydrocarbyl group substituted by halogen such as alkylhalide.

L may be a direct bond or C₁-C₃ hydrocarbylene, more specifically C₁-C₃alkylene.

A represents an n-valent radical wherein n is an integer of 1 to 4. Forexample, A may be hydrocarbyl, hydrocarbylene, a radical having N as abinding site, a radical having S as a binding site, a radical having Pas a binding site, or the like.

For example, the hydrocarbyl may be substituted or unsubstituted C₁-C₂₀alkyl, C₂-C₂₀ alkenyl, or C₆-C₂₀ aryl, and more specifically, forexample, —CH₃, —(CH₂)₃, —(CH₂)₂CH₃, —(CH₂)₇CH₃, —CH₂CH(CH₃)₂, CHCH₂,phenyl, or the like. Herein, n is an integer of 1. Furthermore, when nis 2, the hydrocarbylene may be C₂-C₂₀ alkylene such as (CH₂)₂.

In the case of the radical having N as a binding site, for example, whenn is 1, A may be unsubstituted amine such as *—NH₂ or *—NR₁₁R₁₂, or forexample, substituted amine such as *—NH(CH₂)₂NH₂ or NHCONH₂, or thelike. In addition, when n is 2, A may be *—NR₁₃—* such as *—NH—*,*—NR₁₄CONR₁₅—* such as *—NHCONH—*, *—NR₁₆CSNR₁₇—* such as *—NHCSNH—*, orthe like. Furthermore, when n is 4, A may be

Herein, R¹¹ and R¹² may be independently hydrogen, C₁-C₂₀ alkyl, C₁-C₂₀aminoalkyl, CONH₂, or the like, R¹³ to R¹⁷ may be independently hydrogenor C₁-C₂₀ alkyl, and L₁ may be C₁-C₂₀ alkylene.

The radical having S as a binding site may be for example, *—S—*,*—S—S—*,

and in this case, n is an integer of 2.

Meanwhile, the radical having P as a binding site may be for example,

and in this case, n is an integer of 2 or 3, wherein R¹⁸ and R¹⁹ areindependently hydrogen, C₁-C₂₀ alkyl, C₆-C₂₀ aryl, or(C₁-C₂₀)alkyl(C₁-C₂₀)alkoxy.

In the present disclosure, the silane compound of Chemical Formula 1,wherein n is 1 is, for example, the silane compound wherein L is adirect bond or C₁-C₃ alkylene, A is substituted or unsubstituted C_(l)C₂₀ alkyl, *—NH₂, *—NH—(CH₂)₁—NH₂, *—NH—CO—NH₂, *—C₆H₅, or*—(CH₂)_(m)—C₆H₅, l and m is independently an integer of 1 to 10.

In addition, the silane compound of Chemical Formula 1 wherein n is 2may be the silane compound wherein L is a direct bond or C₁-C₃ alkylene,A is C₁-C₂₀ alkylene, *—NH—*, or *—C(O)—*.

Furthermore, the silane compound of Chemical Formula 1 wherein n is 4may be the silane compound wherein A is

wherein L₁ is C₁-C₁₀ alkylene.

The silane compound represented by Chemical Formula 1 may be, morespecifically for example, the silane compound represented by thefollowing Structural Formula 1 to 28:

Oxygens included in the silane compound are bonded to the surface of theoxide film to protect the oxide film, and may be hydrogen-bonded to thesurface of the oxide film, thereby minimizing etching of the oxide filmduring etching of a nitride in the etchant composition.

In addition, the silane compound described above is a cyclic silanecompound and may be present in the most stable form in the etchantcomposition, and thus, may significantly increase an etch selectionratio as compared with a short chain silicon additive which has beencommonly used. Furthermore, structural stability of the activesilicon-based additive in the etchant composition is improved byincluding the cyclic compound as the above, thereby capable ofconsistently maintaining the etching speed of the silicon oxide film.

Meanwhile, in the above Formula 1, SiO₂H₂O may be precipitated on thesurface of the oxide film to increase a thickness of the oxide film. Thephenomenon is referred to as abnormal growth. In particular, when thephenomenon proceeds by accumulation of the etching process of thenitride in the etchant composition, a concentration of SiO₂H₂O in theetchant composition may be increased, and the increased concentration ofSSiO₂H₂O causes an increase in incidence of the abnormal growth That is,even in the case that the abnormal growth by SiO₂H₂O does not occur inthe initial etchant composition, the incidence of the abnormal growthincreases with the increased number of accumulated processes. However,when the silane compound according to the present disclosure isincluded, occurrence of the abnormal growth phenomenon as such may besuppressed.

The silane compound of the present disclosure may be added in a contentof 0.001 to 1 wt %, based on the total weight of the etchantcomposition. Since the silane compound used in the present disclosurehas two or more silane groups as described above, the silane compound assuggested in the present disclosure may effectively protect a siliconoxide film even in the case of being added in a small amount to theetchant composition, thereby increasing etch selectivity of the nitridefilm to the oxide film. Specifically, when the use amount of the silanecompound is less than 0.001 wt %, it is difficult to obtain an effect ofhigh selectivity to the nitride film to the oxide film, and when the useamount is more than 1 wt %, the silane compound is gelled, which is notpreferred. For example, the silane compound may be used at 0.001 to 1 wt%, 0.001 to 0.7 wt %, 0.002 to 0.7 wt %, 0.002 to 0.5 wt %, 0.005 to 0.5wt %, or the like.

The etchant composition of the present disclosure may further includethe silane compound represented by the following Chemical Formula 2:

wherein R⁵¹ to R⁵⁴ are independently of each other hydrogen,hydrocarbyl, or heterohydrocarbyl, in which R⁵¹ to R⁵⁴ existrespectively or two or more of R⁵¹ to R⁵⁴ form a ring connected to eachother by a heteroelement. For example, R⁵¹ to R⁵⁴ may be hydrogen,C₁-C₂₀ alkyl, C₁-C₂₀heteroalkyl, or the like. Herein, the heteroelementis not particularly limited, but for example, may be N, S, O, P, or thelike.

The silane compound represented by Chemical Formula 2 may be included ina content of 0.005 to 1 wt %, based on the total weight of the etchantcomposition.

Furthermore, an ammonium salt may be added. The ammonium salt mayprevent gelation of the etchant composition, and may be added in acontent of 0.5 to 10 wt %, based on the total weight. When the ammoniumsalt is added at less than 0.5 wt %, a physical property improvementeffect which decreases gelation is insignificant, and when added at morethan 10 wt %, the ammonium salt may be the cause of gelation. Forexample, the ammonium salt may be added in a content of 0.5 to 7 wt %,0.5 to 5 wt %, 0.5 to 3 wt %, 1 to 5 wt %, 1 to 3 wt %, or the like.

The ammonium salt is a compound having an ammonium ion, and thosecommonly used in the art to which the present disclosure pertains may beappropriately used in the present disclosure also. The ammonium salt maybe, for example, ammonia water, ammonium chloride, ammonium acetate,ammonium phosphate, ammonium peroxydisulfate, ammonium sulfate, ammoniumfluorate, or the like, but not limited thereto, and these may be usedalone or in combination of two or more.

Furthermore, the etchant composition of the present disclosure mayfurther include an optional additive commonly used in the art, forfurther improving etching performance. The additive may include asurfactant, a metal ion sequestrant, a corrosion inhibitor, or the like.

The etchant composition of the present disclosure is used forselectively removing a nitride film by etching from a semiconductordevice including an oxide film and a nitride film, and the nitride filmmay include a silicon nitride film, for example, a SiN film, a SiONfilm, or the like.

In addition, the oxide film may be at least one film selected from thegroup consisting of a silicon oxide film, for example, a spin ondielectric (SOD) film, a high density plasma (HDP) film, a thermal oxidefilm, a borophosphate silicate glass (BPSG) film, a phosphosilicateglass (PSG) film, a borosilicate glass (BSG) film, a polysilazane (PSZ)film, a fluorinated silicate glass (FSG) film, a low pressure tetraethylorthosilicate (LPTEOS) film, a plasma enhanced tetraethyl orthosilicate(PETEOS) film, a high temperature oxide (HTO) film, a medium temperatureoxide (MTO) film, an undopped silicate glass (USG) film, a spin on glass(SOG) film, an advanced planarization layer (APL) film, an atomic layerdeposition (ALD) film, a plasma enhanced oxide (Pe-oxide) film, anO3-tetraethyl orthosilicate (O3-TEOS) film, or combinations thereof.

An etching process using the etchant composition of the presentdisclosure may be performed by a wet etching method well-known in theart, for example, dipping, spraying, or the like.

FIGS. 1 and 2 are process sectional views showing a device separationprocess of a flash memory device.

First, as shown in FIG. 1, a tunnel oxide film 11, a polysilicon film12, a buffer oxide film 13, and a pad nitride film 14 are formed in turnon a substrate 10, and then the polysilicon film 12, the buffer oxidefilm 13, and the pad nitride film 14 are selectively etched to form atrench. Subsequently, an SOD oxide film 15 is formed until the trench isgap-filled, and then a CMP process is carried out on the SOD oxide film15 using the pad nitride film 14 as a polishing stop film.

Next, as shown in FIG. 2, the pad nitride film 14 is removed by wetetching using a phosphoric acid solution, and then the buffer oxide film13 is removed by a washing process. As a result, a device separationfilm 15A is formed in a field area.

During the etching process, a process temperature may be in a range of50 to 300° C., preferably 100 to 200° C., more preferably 156 to 163°C., and an appropriate temperature may be changed as requiredconsidering other processes and other factors.

As such, according to a manufacturing method of a semiconductor deviceincluding the etching process which is carried out using the etchantcomposition of the present disclosure, when the nitride film and theoxide film is alternately stacked or mixed, it is possible toselectively etch the nitride film. In addition, particle occurrencewhich was problematic in the conventional etching process may beprevented to secure stability and reliability.

Accordingly, the method may be efficiently applied various processesrequiring selective etching of the nitride film to the oxide film in thesemiconductor device manufacturing process.

EXAMPLE

Hereinafter, the present disclosure will be described in detail by wayof examples. The following Examples relate to an example of the presentdisclosure, but the present disclosure is not limited thereto.

Synthesis Example 1

Silane Compound A

14.9 g of triethanolamine and 23.4 ml of aminopropyl triethoxysilanewere added to a 100 ml round-bottom flask, heated to 130° C. and stirredfor 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving ethanol under a condition of reduced pressure, cooled to normaltemperature, and distilled under reduced pressure to synthesize 21.9 gof purified Silane

Compound A[3-(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-yl)propane-1-amine]represented by the following formula:

¹H-NMR (CDCl₃) 3.66 (t, J=5.5 Hz, 6H), 2.71 (t, J=5.5 Hz, 6H), 2.52 (t,J=7.0 Hz, 2H), 1.42 (qui, J=9.0 Hz, 2H), 1.19 (br, 2H), 2.00 (t, J=8.5Hz, 2H)

Synthesis Example 2

Silane Compound B

14.9 g of triethanolamine and 20.0 ml of methyltriethoxysilane wereadded to a 100 ml round-bottom flask, heated to 130° C. and stirred for2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving ethanol under a condition of reduced pressure, cooled to normaltemperature, and re-slurried with toluene to synthesize 14.4 g ofpurified Silane Compound B[1-methyl-2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecane] representedby the following formula:

¹H-NMR (CDCl₃) 3.68 (t, J=5.5 Hz, 6H), 2.73 (t, J=5.5 Hz, 6H), -0.21 (s,3H)

Synthesis Example 3

Silane Compound C

14.9 g of triethanolamine, 9.7 ml of 1-[3-(trimethoxysilyl)propyl]urea,and 20.0 ml of toluene were added to a 100 ml round-bottom flask, heatedto 110° C. and stirred for 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 2.4 g of Silane Compound C[1-(3-(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-yl)propyl)urea]represented by the following formula:

¹H-NMR (CDCl₃) 3.69 (t, J=5.5 Hz, 6H), 3.39 (t, J=7.0 Hz, 2H), 2.73 (t,J=5.5 Hz, 6H), 1.47 (qui, J=9.0 Hz, 2H), 2.03 (t, J=8.5 Hz, 2H)

Synthesis Example 4

Silane Compound D

9.5 g of triethanolamine, 12.5 g of trimethoxyphenylsilane, and 50 ml oftoluene were added to a 100 ml round-bottom flask, heated to 110° C. andstirred for 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 12 g of Silane Compound D[1-phenyl-2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecane] representedby the following formula:

¹H-NMR (CDCl₃) 7.79-7.77 (m, 1H) 7.32-7.20 (m, 4H), 3.9 (m, 2H), 2.89(m, 2H)

Synthesis Example 5

Silane Compound E

15.0 g of triethanolamine, 117.1 g ofbis[3-(trimethoxysilyl)propyl]amine, 50 ml of toluene, and 0.01 g ofpotassium hydroxide were added to a 100 ml round-bottom flask, heated to120° C. and stirred for 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 21 g of Silane Compound E[bis(3-(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-yl)propyl)amine] represented by the following formula:

¹H-NMR (CDCl₃) 3.75 (t, J=5.5 Hz, 12H), 2.79 (t, J=5.5 Hz, 12H), 2.62(t, J=7.0 Hz, 4H), 1.61 (qui, J=9.0 Hz, 4H), 0.40 (m, 4H)

Synthesis Example 6

Silane Compound F

5.9 g of triethanolamine, 5.3 g of bis(trimethoxysilyl)ethane, 50 ml oftoluene, and 0.01 g of potassium hydroxide were added to a 100 mlround-bottom flask, heated to 120° C. and stirred for 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 14 g of Silane Compound F[1,2-di(2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecan-1-yl) ethane]represented by the following formula:

¹H-NMR (CDCl₃) 3.73 (t, J=5.5 Hz, 12H), 2.73 (t, J=5.5 Hz, 12H), 0.52(s,4H)

Synthesis Example 7

Silane Compound G

19.7 g of 1-[bis(2-hydroxyethyl)amino]-3-chloro-2-propanol, 15 g ofethyltrimethoxysilane, 50 ml of toluene, 0.01 g of potassium hydroxidewere added to a 100 ml round-bottom flask, heated to 120° C. and stirredfor 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 7 g of Silane Compound G[3-(chloromethyl)-1-ethyl-2,8,9-trioxa-5-aza-1-silabicyclo[3,3.3]undecan]represented by the following formula:

¹H-NMR (CDCl₃) 4.53(m, 1H), 3.73 (t, J=5.5 Hz, 4H), 3.38(m, 2H), 3.02(m,2H), 2.73(t, J=5.5 Hz, 4H), 1.40(q, J=9.0 Hz, 2H), 0.90(t, J=9.0 Hz, 3H)

Synthesis Example 8

Silane Compound H

21.7 g of 3-[bis(2-hydroxyethyl)amino]1,1,1-trifluoro-2-propanol, 13.6 gof methyltrimethoxysilane, 50 ml of toluene, 0.01 g of potassiumhydroxide were added to a 100 ml round-bottom flask, heated to 120° C.and stirred for 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 11 g of Silane Compound H [1-methyl3-(trifluoromethyl)-2,8,9-trioxa-5-aza-1-silabicyclo[3,3.3] undecane]represented by the following formula:

¹H-NMR (CDCl₃) 6.32(m, 1H), 3.73 (t, J=5.5 Hz, 4H), 3.07(d, J=6.0 Hz,2H), 2.73(t, J=5.5 Hz, 4H), 0.67(s, 3H)

Synthesis Example 9

Silane Compound I

22.5 g of a-[[bis(2-hydroxyethyl)amino]methyl]benzenemethanol, 15 g ofethyltrimethoxysilane, 50 ml of toluene, 0.01 g of potassium hydroxidewere added to a 100 ml round-bottom flask, heated to 120° C. and stirredfor 2 hours.

Thereafter, the reactants were further stirred for 2 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 5 g of Silane Compound I[1-ethyl-3-phenyl-2,8,9-trioxa-5-aza-1-silabicyclo[3,3.3]un decane]represented by the following formula:

¹H-NMR (CDCl₃) 7.32(m, 2H), 7.25(m, 3H), 5.50(m, 1H), 3.74 (t, J=5.5 Hz,4H), 2.95(m, 2H), 2.77(t, J=5.5 Hz, 4H), 1.43(q, J=9.0 Hz, 2H), 0.85(t,J=9.0 Hz, 3H)

Synthesis Example 10

Silane Compound J

2.0 g of 1-ethenyl-2,8,9-trioxa-5-aza-1-silabicyclo[3,3,3]-undecane, 6.5g of potassium cyanide, 20 ml of DMF, and 20 ml of acetonitrile wereadded to a 100 ml round-bottom flask, and stirred at normal temperaturefor 24 hours.

Thereafter, the solvent was all removed under a condition of reducedpressure. At this time, it was confirmed that a white solid wasproduced.

The solid was re-slurried with 20 ml of toluene, filtered, andvacuum-dried to synthesize 1.5 g of Silane Compound[1-ethenyl-2,8,9-trioxa-5-aza-1-silabicyclo[3,3.3]undecane-4-carbonitrile]represented by the following formula:

¹H-NMR (CDCl₃) 5.45(d, J=7.5 Hz 1H), 5.30(d, J=7.5 Hz, 1H), 5.09(d,J=7.5 Hz, 1H), 4.42(d, J=5.5 Hz, 2H), 3.78 (t, J=5.5 Hz, 4H), 3.07(m,1H), 2.73(t, J=5.5 Hz, 4H)

Synthesis Example 11

Silane Compound K

19.3 g of N,N-bis(2-hydroxyethyl)-L-serine, 13.6 g ofmethyltrimethoxysilane, and 50 ml of toluene were added to a 100 mlround-bottom flask, heated to 120° C. and stirred for 48 hours.

Thereafter, the reactants were further stirred for 12 hours whileremoving methanol under a condition of reduced pressure, and cooled tonormal temperature. At this time, it was confirmed that a white solidwas produced.

The solid was filtered, washed with toluene, and vacuum-dried tosynthesize 10 g of Silane Compound K[1-methyl-2,8,9-trioxa-5-aza-1-silabicyclo[3,3.3]undecane-4-carboxylicacid] represented by the following formula:

¹H-NMR (CDCl₃) 12.22(br, 1H), 4.35(d, J=5.5 Hz, 2H), 3.74 (t, J=5.5 Hz,4H), 2.99(m, 1H), 2.73(t, J=5.5 Hz, 4H), 0.65(s, 3H)

Examples 1 to 11 and Comparative Example 1

Each of Silane Compounds A to K obtained in Synthesis Examples 1 to 11was added to 85% phosphoric acid and mixed therewith so that the contentwas 100 wt % as shown in Table 1, thereby preparing etchant solutions(Examples 1 to 11).

As Comparative Example 1, 0.5 wt % of 3-aminopropylsilanetriol(Comparative Silane Compound 1) was added to 99.5 wt % of 85% phosphoricacid and mixed therewith, thereby preparing an etchant solution(Comparative Example 1), as shown in Table 1.

A substrate in which a silicon oxide (SiOx) film deposited at athickness of 500 angstroms (Å) and a silicon nitride (SiN) filmdeposited at a thickness of 5000 Å were formed on a semiconductor waferwas prepared, and the substrate was etched with the etching solutions ofExamples 1 to 11 and Comparative Example 1, when a temperature of 156°C. or 163° C. was reached.

The wet etching composition was added to a round flask, heated for 60minutes, and when dipping was performed in the above range, the siliconwafer was dipped in the etchant composition for 720 seconds and 6000seconds, respectively.

A surface of the silicon wafer on which a pattern was formed wasselectively etched, and film thicknesses of the silicon oxide film andthe silicon nitride film before and after etching were measured usingthin film thickness measurement equipment (NANO VIEW, SEMG-1000).

The selection ratio represents a ratio of a nitride film etching speed(SiN E/R) to an oxide film etching speed (SiO E/R), and is a valuecalculated by dividing a difference in film thicknesses before and afteretching by an etching time (minute).

Example 12

Silane Compound E obtained in Synthesis Example 5 added to 85%phosphoric acid and mixed therewith so that the content was 100 wt % asshown in Table 1, thereby preparing an etchant solution (Example 12).

The etchant solution of Example 12 was used to etch the silicon nitridefilm and the silicon oxide film in the same manner as in Example 1 onthe same substrate as Example 1.

A selection ratio was measured in the same manner as in Example 1, andthe results are shown in Table 1.

TABLE 1 Process temperature SiN E/R SiO E/R Selection Composition (° C.)(Å/min) (Å/min) ratio Comparative Phosphoric acid (99.5 wt %) + 158 68.30.32 213 Example 1 Comparative Silane Compound (0.5 wt %) Example 1Phosphoric acid (99.5 wt %) + Silane 158 81.3 0.25 365 Compound A (0.5wt %) Example 2 Phosphoric acid (99.5 wt %) + Silane 158 85.6 0.13 658Compound B (0.5 wt %) Example 3 Phosphoric acid (99.5 wt %) + Silane 15882.7 0.27 306 Compound C (0.5 wt %) Example 4 Phosphoric acid (99.5 wt%) + Silane 158 80.5 0.22 366 Compound D (0.5 wt %) Example 5 Phosphoricacid (99.5 wt %) + Silane 158 91.3 0.07 1304 Compound E (0.5 wt %)Example 6 Phosphoric acid (99.5 wt %) + Silane 158 90.7 0.11 824Compound F (0.5 wt %) Example 7 Phosphoric acid (99.5 wt %) + Silane 15894.4 0.04 2360 Compound G (0.5 wt %) Example 8 Phosphoric acid (99.5 wt%) + Silane 158 92.8 0.06 1547 Compound H (0.5 wt %) Example 9Phosphoric acid (99.5 wt %) + Silane 158 83.5 0.21 398 Compound I (0.5wt %) Example 10 Phosphoric acid (99.5 wt %) + Silane 158 89.7 0.12 748Compound J (0.5 wt %) Example 11 Phosphoric acid (99.5 wt %) + Silane158 83.1 0.24 346 Compound K (0.5 wt %) Example 12 Phosphoric acid(99.998 wt %) + Silane 158 80.2 0.18 446 Compound E (0.002 wt %)

As shown in Table 1 above, it is recognized that in Examples 1 to 12, acyclic silane compound which may be present in a stable form in theetchant composition is included to improve structural stability of theactive silicon-based additive, thereby significantly increasing an etchselection ratio, as compared with Comparative Example 1 including asilane compound having a short chain structure. Thus, the etching speedof the silicon oxide film may be consistently improved.

The etchant composition according to the present disclosure has a highetching selection ratio of a nitride film to an oxide film, by includinga silane compound which is reacted with a surface of an oxide film toform a protective film capable of protecting the oxide film.

In addition, use of the etchant composition of the present disclosureprevents damage of film quality of the oxide film when removing thenitride film or deterioration of electrical properties due to etching ofthe oxide film, thereby improving device characteristics.

In particular, the present disclosure uses the silane compound having asilatrane structure to maintain a stable structure in the etchantsolution, thereby obtaining an excellent selection ratio even with theaddition of a small amount.

While exemplary embodiments have been shown and described above, it willbe apparent to those skilled in the art that modifications andvariations could be made without departing from the scope of the presentinvention as defined by the appended claims.

What is claimed is:
 1. An etchant composition comprising: phosphoricacid and a silane compound represented by the following Chemical Formula1:

wherein R¹ to R⁶ are independently hydrogen, halogen, a substituted orunsubstituted C₁-C₂₀ hydrocarbyl group, a C₁-C₂₀ alkoxy group, a carboxygroup, a carbonyl group, a nitro group, a tri (C₁-C₂₀)alkylsilyl group,a phosphoryl group, or a cyano group, L is a direct bond or C₁-C₃hydrocarbylene, A is an n-valent radical, and n is an integer of 1 to 4.2. The etchant composition of claim 1, wherein the substituted orunsubstituted C₁-C₂₀ hydrocarbyl group is a substituted or unsubstitutedC₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₂₀ aryl group.3. The etchant composition of claim 2, wherein the substituted C₁-C₂₀hydrocarbyl group is substituted by halogen.
 4. The etchant compositionof claim 1, wherein A is hydrocarbyl, hydrocarbylene, a radical having Nas a binding site, a radical having S as a binding site, or a radicalhaving P as a binding site.
 5. The etchant composition of claim 4,wherein the hydrocarbyl is C₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, or C₆-C₂₀ aryl.6. The etchant composition of claim 4, wherein the radical having N as abinding site is *—NR¹¹R¹², *—NR¹³—*, *—NR¹⁴CONR¹⁵—*, *—NR¹⁶CSNR¹⁷—*, or

wherein R¹¹ and R¹² are independently hydrogen, C₁-C₂₀ alkyl, C₁-C₂₀aminoalkyl, or CONH₂, R¹³ to R¹⁷ are independently hydrogen or C₁-C₂₀alkyl, and L₁ is C₁-C₂₀ alkylene.
 7. The etchant composition of claim 4,wherein the radical having S as a binding site is *—S—*, *—S—S—*,


8. The etchant composition of claim 4, wherein the radical having P as abinding site is

wherein R¹⁸ and R¹⁹ are independently hydrogen, C₁-C₂₀ alkyl, C₆-C₂₀aryl, or (C₁-C₂₀)alkyl(C₁-C₂₀)alkoxy.
 9. The etchant composition ofclaim 1, wherein n is 1, L is the direct bond or C₁-C₃ alkylene, A issubstituted or unsubstituted C₁-C₂₀ alkyl, substituted or unsubstitutedC₁-C₂₀ alkenyl, *—NH₂, *—NH—(CH₂)₁—NH₂, *—NH—CO—NH₂, or*—(CH₂)_(m)—C₆H₅, and 1 and m is independently an integer of 0 to 10.10. The etchant composition of claim 1, wherein n is 2, L is a directbond or C₁-C₃ alkylene, A is C₁-C₂₀ alkylene, *—NR¹³—*,*—NR¹⁴—CO—NR¹⁵—*, *—S—*,

*—S—S—*, and R¹³ to R¹⁵, R¹⁸, and R¹⁹ are independently hydrogen, C₁-C₂₀alkyl, C₆-C₂₀ aryl, or (C₁-C₂₀)alkyl(C₁-C₂₀)alkoxy.
 11. The etchantcomposition of claim 1, wherein n is 3, L is a direct bond or C₁-C₃alkylene, and A is


12. The etchant composition of claim 1, wherein n is 4, L is C₁-C₃alkylene, and A is

wherein L₁ is C₁-C₁₀ alkylene.
 13. The etchant composition of claim 1,wherein R¹ is hydrogen or substituted or unsubstituted hydrocarbyl, andR² to R⁶ are hydrogen.
 14. The etchant composition of claim 1, whereinthe silane compound is selected from the following structures:


15. The etchant composition of claim 1, wherein the silane compoundrepresented by Chemical Formula 1 is included in an amount of 0.001 to 1wt %, based on a total weight of the etchant composition.
 16. Theetchant composition of claim 1, further comprising a silane compoundrepresented by the following Chemical Formula 2:

wherein R⁵¹ to R⁵⁴ are independently hydrogen, hydrocarbyl, orheterohydrocarbyl, in which R⁵¹ to R⁵⁴ exist respectively or two or moreof R⁵¹ to R⁵⁴ form a ring connected to each other by a heteroelement.17. The etchant composition of claim 16, further comprising an ammoniumsalt.
 18. A method of etching an insulating film using the etchantcomposition of claim 1.